Light sensitive colloid layers and tanned pictures therefrom



. Patented Nov. 16, 1937 I UNITED". STATES LIGHT SENSITIVE COLLOD) LAYERS AND TANNED PICTURES THEREFROM Gustav Kiigel, Baden-Baden, and Rudolf Zalm, 'Wiesbaden, Germany, assignors to Kalle & Co. Aktiengesellsohait, Wiesbaden-Biebrlch, Germany No Drawing. Application January 10, 1935, Se-

rial No. 1,238. In Germany January 19, 1934 8 Claims.

The present invention' relates to colloid layers sensitized by means of aromatic nitro-compounds, and to a process of preparing tanned pictures therefrom.

We have found that photographic materials with excellent properties are obtained by rendering colloid layers sensitive to light by the addition of aromatic nitro-compounds capable of yielding, when exposed to light, products which have tanning properties for the colloid. It has further been found that distinguished tanned pictures or copies can be obtained by exposing the said light sensitive colloid layers to light beneath r a pattern and then operating on them in a manner known per se, so as to produce tanned copies.

The colloid layers according to the invention are rendered light sensitive by various aromatic nitro compounds which, when exposed to' light, yield decomposition products capable of tanning the colloid substance of the layer. Preferably nitro derivatives of the benzene and naphthalene series may be employed as light sensitive substances. a-nitro-naphthaiene compounds which are substituted by a carboxylic group or a suite group, preferably in the orthoor in the periposition to the nitro group 'have proved very suitable. For water-soluble colloids there may be employed nitro compounds which are likewise soluble in water, such as, for example, l-nitronaphthaiene-il-sulphonic acid, .l-nitronaphthalene-2-sulphonic acid, l-nitronaphthalene-dcarboxylic acid, l-nitronaphthalene-3.8-disulphonic acid, l-nitro-B-methylnaphthaleneisulphonic acid. The said nitro compounds may also have further substltuents (such as, for example, halogens). For colloids soluble in alcohol or hydrocarbons, l-methyl-8-nitronaphthalene and l-nitronaphtha.lene-8-carboxylic acid are, for example, suitable. The light sensitiveness may be increased by the addition of metallic salts, for example cerium salts, or of amines, for example amline, to the layers, or the-exposed layers maybe ai'tertreatedwith salts, such as chromates, cerium salts and so forth.

5 As colloids for the new process natural colloids 1 of the most varied kinds, such as glue, resins, the saps or juices of plants and in particular gelatine and so forth, and furthermore synthetic colloids, such as, for example, .cellulose-derivatives 50 as methyl cellulose or artificial resins, may be employed. The colloid best adapted for a given nitro compound may easily be determined. According to the present invention tanned pictures are. obtained by exposingthe described 5 colloid layers to light beneath a pattern and subjecting them to a suitable after-treatment which develops and/or fixes the image produced by the exposure. In this process the image is produced as a result of the fact that the light sensitive nitro compounds employed tan the colloid layer under the action of light, 1. e. the capability of adsorbing moisture and the solubility of the colloidal substance employed is lessened at the places struck by the light. By treatment with a suitable solvent the colloid not tanned by the action of light can be removed while the tanned colloid at the places struck by the light remains. The obtained relief may for example be coloured, or may be employed for direct printing according to the manner of the photographic printing process. If the colloid contains a pigment in addition to the light sensitive substance pigment prints can be produced. If the layer is applied in suitable manner to metal or stone, autotypes or photo lithographs can be produced. Layers of this kind are also suitable for copper plate intaglio printimage, is transferred by means of a 1% solution of cerium-chloride to transfer paper and is developed with water at C. A positive laterally inverted copy of the original is obtained. The transferring operation may advantageously also be carried outwith weakly alkaline solutions (for example an ammonia solution) In place of the 1.8-nitronaphthalene sulphonic acid, 1.2-nitronaphthalene sulphonic acid and the 1.3.8-nitronaphthalene disulphonic acid or their salts respectively may be employed.

(2) 3.5 grammes of gelatine are dissolved in grammes of water and are mixed with a solution of l gramme orthonitrobenzylalcohol in 40,

grammes of alcohol. This emulsion is poured out in' a thin layer on to a copper plate and dried. Then the layer is exposed under an auto-type negative and washed out with warm water. v After drying the etching operation is, carried out in the customary manner with iron chloride. 4

(3) 2.5 grammes of gelatine are dissolved in 40 grammes of water, are colouredwith 1.5 grammesv of a finely divided pigment and rendered sensitive to light by means of. a solution" of 0.5 grammes of the sodium salt of 4-nitronaphtha- 1ene-1.8-dicarboxylic acid in 40 grammes of water. The mixture is spread on paper in a thin layer. The dried paper is exposed to light beneath a pattern, which is preferably free from half-tones. The image is developed with water at 40 C.

(4) Pigment paper of commercial use is bathed in a solution of 6 grammes of the sodium salt of l-nitro-8-methylnaphthalene-4-sulphonic acid in 100 grammes of water until it is stretched completely. The paper is then pressed on a glass base with its gelatinized side and dried without heating. A stable light sensitive paper is obtained. which may be employed in the usual manner.

3 grammes of hard gelatine are dissolved in 40 grammes of water and the solution is mixed with 3 grammes of finely powdered asphalt. A solution of 0.8 grammes of the sodium salt of 1-nitronaphthalene-8-carboxylic acid in 50 grammes of water is then added. This emulsion is poured on to a zinc plate in a thin layer and dried. The material is exposed beneath a negative and washed out with warm water. The dried layer is made etch-fast by a heating process and the zinc plate is then etched in the customary manner.

We claim:

1. Process for the production of tanned pictures i the following general formula:

wherein R is a naphthalene residue with the nitro group in alpha-position, and X stands for a member of the group consisting of the COOH group and the SOaH group, under a pattern and then dissolving the colloid not tanned by the action of 3. Process for the production of tanned pictures which comprises exposing a gelatine layer sensitized by means of 1.8-nitro-naphthalene sulionic acid under a pattern and then dissolving the colloid not tanned by the action of light.

4. Process for the production of tanned pictures which comprises exposing a gelatine layer sensitized by means of 1.8-nitro-naphthalene carboxylic acid under a pattern and then dissolving the colloid not tanned by the action of light.

5. Process for the production of tanned pictures which comprises exposing a gelatine layer sensitized by means of ortho-nitrobenzyl alcohol under a pattern and then dissolving the colloid not tanned by the action of light.

6. Process for the production of tanned pictures which comprises exposing a light-sensitive layer comprising a colloidal substance capable of being tanned, a pigment and a light-sensitive nitro compound of the following general formula:

layer comprising a gelatinous substance capable of being tanned and a light-sensitive nitro compound of the following general formula:

wherein R is a naphthalene residue with the nitro group in alpha position, and X stands for a member of the group consisting of the COOH group and the 803K group, under a pattern and then dissolving the colloid not tanned by the action of light.

8. Process for the production of tanned pictures which comprises exposing a light-sensitive layer comprising a gelatinous substance capable of being tanned and a light-sensitive alpha-nitronaphthalene compound which is substituted in the peri-position to the nitro group by a suite group, under a pattern and then dissolving the colloid not tanned by the action of light.

GUSTAV' KCiGEL. RUDOLF ZAHN. 

